Dec 22, 2025 · Dec 22, 2025 · Dec 22, 2025
diff --git a/Include/internal/pycore_tracemalloc.h b/Include/internal/pycore_tracemalloc.h
        TRACEMALLOC_FINALIZED
    } initialized;

    /* Is tracemalloc tracing memory allocations?
       Variable protected by the TABLES_LOCK(). */
    /* Is tracemalloc tracing memory allocations? (Atomic.) */
    int tracing;

    /* limit of the number of frames in a traceback, 1 by default.
diff --git a/Python/tracemalloc.c b/Python/tracemalloc.c

    /* everything is ready: start tracing Python memory allocations */
    TABLES_LOCK();
    tracemalloc_config.tracing = 1;
 _Py_atomic_store_int_release(&tracemalloc_config.tracing, 1);
    TABLES_UNLOCK();

    return 0;
    }

    /* stop tracing Python memory allocations */
    tracemalloc_config.tracing = 0;
 _Py_atomic_store_int_release(&tracemalloc_config.tracing, 0);

    /* unregister the hook on memory allocators */
    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);
 PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
                    size_t size)
 {
    if (!_Py_atomic_load_int_relaxed(&tracemalloc_config.tracing)) {
        // Exit early without attempting to lock if it doesn't look like
        // we're tracing.
        return -2;
    }

    PyGILState_STATE gil_state = PyGILState_Ensure();
    TABLES_LOCK();

        result = tracemalloc_add_trace_unlocked(domain, ptr, size);
    }
    else {
        /* tracemallocis not tracing:do nothing */
        /* tracemallocwas disabled before we locked tables;do nothing. */
        result = -2;
    }

 int
 PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr)
 {
    if (!_Py_atomic_load_int_relaxed(&tracemalloc_config.tracing)) {
        // Exit early without attempting to lock if it doesn't look like
        // we're tracing.
        return -2;
    }
    TABLES_LOCK();

    int result;
        result = 0;
    }
    else {
        /* tracemallocis not tracing:do nothing */
        /* tracemallocwas disabled before we locked tables;do nothing. */
        result = -2;
    }
Original file line number	Diff line number	Diff line change
Expand Up		@@ -20,8 +20,7 @@ struct _PyTraceMalloc_Config {
		TRACEMALLOC_FINALIZED
		} initialized;

		/* Is tracemalloc tracing memory allocations?
		Variable protected by the TABLES_LOCK(). */
		/* Is tracemalloc tracing memory allocations? (Atomic.) */
		int tracing;

		/* limit of the number of frames in a traceback, 1 by default.
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Original file line number	Diff line number	Diff line change
Expand Up		@@ -850,7 +850,7 @@ _PyTraceMalloc_Start(int max_nframe)

		/* everything is ready: start tracing Python memory allocations */
		TABLES_LOCK();
		tracemalloc_config.tracing = 1;
		_Py_atomic_store_int_release(&tracemalloc_config.tracing, 1);
Copy link Contributor kumaraditya303Dec 22, 2025 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. I think release is stronger than necessary because there are no data dependencies. The actual functions are called with the lock held anyways so only atomicity of`tracing` matters. Copy link MemberAuthor Yhg1sDec 22, 2025 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. I think thereis a hidden data dependency: we don't want tracing to be enabled, an allocation to be tracked, and then another thread deallocating that tracked data without untracking.
		TABLES_UNLOCK();

		return 0;
Expand All		@@ -867,7 +867,7 @@ _PyTraceMalloc_Stop(void)
		}

		/* stop tracing Python memory allocations */
		tracemalloc_config.tracing = 0;
		_Py_atomic_store_int_release(&tracemalloc_config.tracing, 0);

		/* unregister the hook on memory allocators */
		PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);
Expand DownExpand Up		@@ -1207,6 +1207,12 @@ int
		PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
		size_t size)
		{
		if (!_Py_atomic_load_int_relaxed(&tracemalloc_config.tracing)) {
		// Exit early without attempting to lock if it doesn't look like
		// we're tracing.
		return -2;
		}

		PyGILState_STATE gil_state = PyGILState_Ensure();
		TABLES_LOCK();

Expand All		@@ -1215,7 +1221,7 @@ PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
		result = tracemalloc_add_trace_unlocked(domain, ptr, size);
		}
		else {
		/* tracemallocis not tracing:do nothing */
		/* tracemallocwas disabled before we locked tables;do nothing. */
		result = -2;
		}

Expand All		@@ -1228,6 +1234,11 @@ PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
		int
		PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr)
		{
		if (!_Py_atomic_load_int_relaxed(&tracemalloc_config.tracing)) {
		// Exit early without attempting to lock if it doesn't look like
		// we're tracing.
		return -2;
		}
		TABLES_LOCK();

		int result;
Expand All		@@ -1236,7 +1247,7 @@ PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr)
		result = 0;
		}
		else {
		/* tracemallocis not tracing:do nothing */
		/* tracemallocwas disabled before we locked tables;do nothing. */
		result = -2;
		}

Expand Down